There are many agents that are used for producing a beneficial effect that have serious shortcomings associated with their use. Many of these agents are drugs known to pharmacentical science. For example, the electrolyte potassium chloride is the salt most frequently used when the action of the potassium cation is desired for an indicated therapeutic effect. Potassium chloride is used when hypokalemia exists, as a treatment with certain diuretics, in steroid therapy, and for relieving the symptoms of Menier's disease. However, serious shortcomings are associated with its uses, mainly concentrated preparations of potassium chloride are an irritant to the gastrointestional tract, and its use often leads to bowel lesions. Another important agent-drug that possesses similar shortcomings is aspirin. Aspirin, or acetalsalicylic acid, is widely used as an antipyretic and analygetic in a variety of medical conditions. Aspirin is a very potent drug; however, occult gastrointestinal bleeding often follows the use of conventional, concentrated dosage forms of the drug. One additional example of a useful drug whose usefulness often is compromised by unwanted effects is indomethacin. Indomethacin is a nonsteroidal indole that exhibits both analgesic and anti-inflammatory properties, and it is used most for the treatment of rheumatoid arthritis. The most frequent untoward actions associated with concentrated dosage forms containing this drug are gastrointestinal disturbances similar to those mentioned above.
The prior art has provided novel osmotic therapeutic systems manufactured in the form of osmotic devices for the precision administration of drugs with control of delivery patterns and with extended operational delivery times. Those systems are known in U.S. Pat. Nos. 3,845,770 and 3,916,899, both issued to patentees Felix Theeuwes and Takeru Higuchi. The patents are assigned to the ALZA Corporation of Palo Alto, Calif. The systems disclosed in these patents are made of a semi-permeable wall that surrounds a reservoir containing a drug. The systems disclosed in these patents are extraordinarly effective for delivering all kinds of drugs in the form of saturated solution over time. While the above systems represent an outstanding and pioneering advancement in the delivery art, and while they are useful for dispensing innumerable drugs to the biological environment of use, there is an occasional instance when a less than saturated solution is needed for a therapeutic indication. These instances are exemplified by the above mentioned prior art. Thus, in the light of this presentation, it will be appreciated by those versed in the dispensing art that if a system is made available for dispensing beneficial agents, including drugs, that dispenses the agents in less than concentrated amounts, such systems would have a definite use and represent a valuable contribution to the art.